【Manacher算法】求最长回文串的优秀算法

先贴一下代码~

//by 减维
#include<cstdio>
#include<iostream>
#include<cstring>
#include<queue>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<algorithm>
#define ll long long
#define maxn
using namespace std;

char s[],a[];
int nxt[],mr,pos,ans;

int main()
{
    char ch=getchar();
    a[]='#';a[]='#';
    gets(s+);int ls=strlen(s+);
    for(int i=;i<=ls;++i)a[i*]=s[i],a[i*+]='#';int n=ls*+;
    for(int i=;i<=n;++i){
        if(mr>i)nxt[i]=min(nxt[*pos-i],mr-i);
        else nxt[i]=;
        while(a[i-nxt[i]]==a[i+nxt[i]])nxt[i]++;
        if(i+nxt[i]>mr)mr=i+nxt[i],pos=i;
        ans=max(ans,nxt[i]-);
    }
    printf("%d",ans);
}